But former fire chief Brian Potter says a bill introduced into Victoria's parliament on Wednesday will make it easier for cancer-stricken firefighters to make compensation claims.

The former Country Fire Authority (CFA) chief and Fiskville whistleblower has suffered ill-health and cancer for almost two decades.

He made a claim for compensation that was knocked back because he could not prove the link between his workplace and his cancer.

Mr Potter said the Greens bill would put an end to firefighters who have developed cancer having to battle individually with the fire services insurer every time.

He said one of the dilemmas firefighters faced was a requirement to quote the incident they were at and the materials that were burning that led to their cancer.

"Some of my cases for example, they were 40-odd years ago," he told reporters in Melbourne.

"Everyone who was there that might be able to corroborate my statements are dead.

"Today is a move that will finally alleviate that problem."

Mr Potter, who lifted the lid on dangerous practices at CFA's Fiskville training base northwest of Melbourne, said the day brought mixed emotion.

"It's tinged with sadness of course, because so many of my colleagues have died waiting to see this happen," he said.

"But I think they themselves and their families and friends would be relieved to know that we now can see a glimmer of hope for firefighters in the future."

Victorian Greens MP Colleen Hartland, who introduced the bill, said it would remove barriers faced by professional and volunteer firefighters in accessing WorkCover compensation and insurance if they get cancer from exposure to toxic chemicals and smoke on the job.

The proposed law aims to reverse the onus of proof, so if a firefighter suffers from one of 12 specified cancers shown to be common among firefighters, it will be considered work-related unless proved otherwise.

Such protections are already in place for firefighters employed by the Commonwealth.

United Firefighters Union national secretary Peter Marshall backed the move.

"Workers and volunteers are usually protected by WorkCover or insurance when they contract serious injury, but with cancer it is almost impossible to prove which fires and which dates are responsible, out of the thousands of incidents that firefighters have faced," he said.

Volunteer Fire Brigades Victoria chief executive Andrew Ford said the changes would enable a firefighter to concentrate on treatment and recovery, rather than proving how disease was caused.

Premier Ted Baillieu says there are "complexities" to work through before his government supports the bill.

Opposition emergency services spokeswoman Jacinta Allan said the opposition supported the principle behind the new laws and would work with all parties to progress the bill through parliament.

Last year, the CFA apologised for "draconian" practices that put about 87,000 people at risk of exposure to carcinogens at the Fiskville training site over three decades.

An independent report on Fiskville declared the training ground now safe, but hundreds of firefighters have potentially had their health affected.